Q2 BULLETIN 173, U. S. NATIONAL MUSEUM 



SICKELS DROP CUT-OFF VALVE GEAR, 1841 



PlATE 16, FiGXJBE 1 



U.S.N.M. no. 180973 ; model ; deposited by Frederick E. Sickels ; photograph 

 no. 32595. 



This is a nicely made brass duplicate of the original Patent Office 

 model (see above) of the Sickels valve gear, deposited in the Museum 

 by Frederick E. Sickels, the inventor, in 1891. 



The Museum has a certificate (U.S.N.M. no. 180974), dated April 

 8, 1891, stating "that the annexed (this model) is a duplicate of the 

 model filed in the matter of the Letter Patent granted to Frederick 

 E. Sickels, May 20, 1842 for Improvement in Lifting, Tripping and 

 Regulating the Closing of Steam Valves." This is signed by C. E. 

 Mitchell, Commissioner of Patents, and sealed with the seal of the 

 Patent Office. 



ALLEN ADJUSTABLE CUT-OFF VALVE GEAR, 1841 



Plate 16, Figure 2 



U.S.N.M. no. 308649; original patent model; transferred from the United States 

 Patent Office; photograph no. 32595B. 



This model was submitted with the application for the patent issued 

 to Horatio Allen, of New York, N. Y., August 21, 1841, no. 2227. 



This is a very early example of an adjustable riding cut-off valve 

 in which the riding valve is formed in two parts provided with a 

 suitable mechanism to vary the distance between the two parts and 

 thus vary the cut-off. 



The model represents a double-acting, horizontal, direct-connected 

 engine with flat slide valve and riding cut-off valve driven by sepa- 

 rate eccentrics on the crankshaft. The model is of a section through 

 the cylinder and valve chest of the engine. The model shows a long 

 D -slide valve with ports through a projection of the valve instead 

 of the usual steam edge. Steam is admitted and cut off through these 

 ports, which are opened and closed by the riding valve. The main 

 valve operates as a simple slide valve, while the riding valve per- 

 forms the function of cutting off the steam. The riding valve is 

 in two parts carried on a rod threaded through lugs on the valves 

 with one right-hand and one left-hand thread, so that turning the 

 rod moves the parts of the valve away from or toward each other. 

 The farther apart the two parts are, the earlier the cut-off will oc- 

 cur. A bevel gear and spline on the threaded rod permits the adjust- 

 ment to be made without stopping the engine. 



The patent refers to other ways of obtaining an adjustable cut-off 

 and suggests that the second eccentric be dispensed with and motion 

 for the riding valve be taken directly from the engine cross head. 



The inventor refers to his invention as an improvement on the 

 Isaac Adams riding cut-off valve patented in May 1838. 



